The present invention relates to multiple access systems and more specifically to encoding techniques for multiple access systems. In a general DS-CDMA system the multiple access interference (MAI) in each receiver increases along with the number of users in the system and therefore the capacity of a given frequency is limited.
Prior art methods and systems have looked to MAI cancellation and have focused on the receiver. For example, S. Verdu, “Minimum probability of error for asynchronous Gaussian multiple-access channels,” IEEE Trans. Inform. Theory, Vol. IT-32, pp. 85-86, January 1986 reported a receiver that outperforms a linear correlation receiver. In these receiver designs, however, the computational complexity exponentially increases with the number of transmitters.